1. Field of the Invention
The present invention relates to a technique of forming interconnects of a semiconductor device. In particular, the present invention relates to a semiconductor device, which is provided with several interconnects having different thickness in the same layer, and to a method of manufacturing the same device.
2. Description of the Related Art
Recently, it is general that interconnects provided in a semiconductor device are formed using a burying process calling a damascene process. Of these interconnects provided in the semiconductor device, a fuse interconnect exists in addition to an interconnect provided as an ordinary conducting path. The fuse interconnect is provided for the purpose of breaking a conducting path with failure circuits, for example. It is preferable that ordinary interconnects are formed thicker to reduce the interconnect resistance. On the contrary, it is preferable that the fuse interconnect is formed thin because it is hard to be blown if formed thick.
According to an ordinary damascene process, if several interconnects are formed in an interlayer insulating film of the same layer, it is general that the following process is carried out. Specifically, in order to improve work efficiency, several trenches for providing the foregoing interconnects are collectively formed via one-time etching process. Of course, if the interlayer insulating film is formed of a single material, trenches formed via one-time etching process all have the approximately same depth. For this reason, according to the ordinary damascene process, it is difficult to form the foregoing several interconnects having different thickness in the interlayer insulating film of the same layer. If several trenches having different depth are formed in the interlayer insulating film of the same layer using the ordinary damascene process, the etching process increases; as a result, work efficiency is reduced. The foregoing technique is disclosed in JPN. PAT. APPLN. KOKAI Publication No. 2002-76129, for example.